The present invention relates to apparatus for adding toner to an electrographic development station.
During operation of electrographic apparatus particles of toner from a development station are used to develop a latent electrostatic image on a photoconductor. The toner particles thus depleted from the development station must be periodically replaced using apparatus that is easy for the operator to use, avoids contamination of the electrographic apparatus, and utilizes toner containers that are relatively inexpensive in view of the relatively large quantities of such containers that are used over a period of time.
It is known to provide fresh toner directly from a container to the development station of electrographic apparatus. In some instances the toner is metered to the development apparatus by a toner dispenser between the container and the sump of the development apparatus, and in other instances the full container of toner can be emptied directly into a sump and conveyed to a magnetic brush or the like for applying toner to a photoconductor. Such apparatus is disclosed, for example, in U.S. Pat. Nos. 3,954,331, 3,981,272 and 4,344,692. In other cases the container is placed on the development station and dispensed to the station only after removal of a closure plate or tear strip as disclosed, for example, in U.S. Pat. Nos. 4,237,943 and 4,062,385.
The known apparatus requiring specialized containers having closure plates or tear strips which are removed after the container is mounted on the development station may work well and be clean with little likelihood of contamination of the apparatus. However, because each such container must be provided with a special closure plate or tear strip, they are more expensive than "standard" off the shelf containers. Clearly it would be advantageous to use a standard container. Other of the apparatus disclosed in the patents require movement of parts of the development apparatus, such as a toner metering mechanism, or they may require a relatively large amount of space in the development station. However, it is desirable to minimize movement of parts of the development station when toner is being added, and to minimize the space required for loading fresh toner into a development station. This is especially important when the electrographic apparatus has several development stations for developing images with toners of different colors.